Religious conservatives should cut off all contributions to the Republican Party — until it grows a "backbone" and stops waffling on social issues like gay marriage, a leading conservative Christian group says.

In an email to supporters obtained by CNN, Tony Perkins, president of the Family Research Council, slammed the Republican National Committee for its suggestion that the GOP should reconsider its take on same-sex marriage to attract younger voters.

"Until the RNC and the other national Republican organizations grow a backbone and start defending core principles, don’t send them a dime of your hard-earned money," Perkins said.

"If you want to invest in the political process, and I encourage you to do so, give directly to candidates who reflect your values and organizations you trust — like FRC Action."

Perkins charged that the RNC’s recommendation — contained in a sweeping report it commissioned to find ways to fix the party after Mitt Romney’s defeat last year — will only repel young voters who don’t approve of same-sex unions.

"There’s an entire group of 'Countercultural Warriors' full of compelling young leaders who are all going to the mat to protect marriage."

The Family Research Council, considered the nation’s top conservative religious group with strong political lobbying abilities, also joined other groups in sending a letter to the RNC earlier this week urging the party to stand its ground against same-sex marriage.

The RNC is hold its spring meeting in California this week and was scheduled to take up a resolution Friday reaffirming its position opposing gay marriage.